These functions mainly support the extraction system, but are
maintained in the main program and are therefor accepted in feature
sets where the extraction system is disabled.

Many of the layer-related functions take a ``standard layer
argument''. This can be an integer index number into the layer table,
where the index is 1-based, and values less than 1 return the current
layer. The argument can also be a string, giving a layer name in layer[:purpose] form, or an alias name. If the
string is null or empty, the current layer is returned.

(string) SetLayerExKeyword(stdlyr, string)
The first argument is a standard layer argument indicating a physical
layer, or a derived layer name string. The string argument is
an extraction keyword and associated text, as would appear in a layer
block in the technology file. The specification will be applied to
the layer, overriding existing settings and possibly causing
incompatible or redundant existing keywords to be deleted. This is
similar to the editing functions of the Tech Parameter Editor
from the Attributes Menu, when using the Extract or Physical pages.

(string) SetCurLayerExKeyword(string)
This is similar to SetLayerExKeyword, but applies to the current
layer. This function is deprecated and not recommended for use in new
scripts.

(int) RemoveLayerExKeyword(stdlyr, keyword)
The first argument is a standard layer argument indicating a physical
layer, or a derived layer name string. This will remove the
specification for the extract keyword given in the argument from the
layer. The argument must be one of the extraction keywords, i.e.,
those listed for SetCurLayerExKeyword. The return value is 1 if
a specification was removed, 0 otherwise.

(int) RemoveCurLayerExKeyword(keyword)
This is similar to RemoveLayerExKeyword but applies to the
current layer. This function is deprecated and not recommended for
use in new scripts.

(int) IsLayerConductor(stdlyr)
The function returns 1 if the Conductor keyword is given or
implied for the layer indicated by the argument, which is a standard
layer argument or a derived layer name string, 0 otherwise.

(int) IsLayerRouting(stdlyr)
The function returns 1 if the Routing keyword is given for the
layer indicated by the argument, which is astandard layer argument or
a derived layer name string, 0 otherwise.

(int) IsLayerGround(stdlyr)
The function returns 1 if one of the GroundPlane keywords was
given for the layer indicated by the argument, which is a standard
layer argument or a derived layer name string, 0 otherwise.

(int) IsLayerContact(stdlyr)
The function returns 1 if the Contact keyword is given for the
layer indicated by the argument, which is a standard layer argument or
a derived layer name string, 0 otherwise.

(int) IsLayerVia(stdlyr)
The function returns 1 if the Via keyword is given for the layer
indicated by the argument, which is a standard layer argument or a
derived layer name string, 0 otherwise.

(int) IsLayerDielectric(stdlyr)
The function returns 1 if the Dielectric keyword is given for
the layer indicated by the argument, which is a standard layer
argument or a derived layer name string, 0 otherwise.

(int) IsLayerDarkField(stdlyr)
The function returns 1 if the DarkField keyword is given or
implied for the layer indicated by the argument, which is a standard
layer argument or a derived layer name string, 0 otherwise.

(real) GetLayerThickness(stdlyr)
The function returns the value of the Thickness parameter given
for the layer indicated by the argument, which is a standard layer
argument or a derived layer name string.

(real) GetLayerRho(stdlyr)
The function returns the resistivity in ohm-meters of the layer
indicated by the argument, which is a standard layer argument or a
derived layer name string, as given by the Rho or Sigma
parameters, if given. If neither of these is given, and Rsh and
Thickness are given, the return value will be Rsh*Thickness.

(real) GetLayerResis(stdlyr)
The function returns the sheet resistance for the layer indicated
by the argument, which is a standard layer argument or a derived layer
name string. This will be the value of the Rsh parameter, if
given, or the values of Rho/Thickness, if Rho or
Sigma and Thickness are given, or 0 if no value is
available.

(real) GetLayerEps(stdlyr)
The function returns the relative dielectric constant for the layer
indicated by the argument, which is a standard layer argument or
derived layer name string, as given by the EpsRel parameter if
applied.

(real) GetLayerCap(stdlyr)
The function returns the per-area capacitance for the layer indicated
by the argument, which is a standard layer argument or a derived layer
name string.

(real) GetLayerCapPerim(stdlyr)
The function returns the per-perimeter capacitance for the layer
indicated by the argument, which is a standard layer argument or a
derived layer name string.

(real) GetLayerLambda(stdlyr)
The function returns the value of the Lambda parameter for the
layer indicated by the argument, which is a standard layer argument or
a derived layer name string.